first lets see how much he spent on rides
1.25 x 25 = 31.25
that means he spent $12.5 on admission (43.75 - 31.25)
y = 43.75
x = 25
1.25 is non dependent
b (y-intercept) = 12.5 because thats what you start off spending to get in.
y = 1.25x + 12.5
check your work
43.75 = 1.25(25) + 12.50
43.75 = 31.25 + 12.50
43.75 = 43.75